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Markus Ost - One of the best experts on this subject based on the ideXlab platform.
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experience attracts the role of age in the formation of cooperative Brood Rearing coalitions in eiders
Animal Behaviour, 2011Co-Authors: Kim Jaatinen, Markus OstAbstract:Lacking experience represents a constraint on solitary breeding, which may be overcome by joining groups of more experienced breeders. Also, biological market theory predicts preference for partnerships with conspecifics of the highest value. We examined the formation of cooperative Brood-Rearing coalitions in facultatively social eider females, Somateria mollissima. Our aim was to elucidate the hitherto neglected role of age on female group size and condition differences within groups, and to explore whether older females represent attractive coalition partners. Based on previous work, we hypothesized that older breeders are found in smaller groups, and that the attraction of older partners would override the predicted negative effect of differences in body condition on female group size. We found that older females occurred in smaller groups and that the negative relationship between condition differences and group size became less steep with increasing age of the oldest group member. We also found that the maximum body condition found in a Brood-Rearing coalition increased with the age of the oldest female, despite a sharp decline in the probability of the oldest individual being the one in best condition. These results demonstrate the importance of age in the formation of cooperative Brood-Rearing coalitions and the increase in female quality with age. The experience of older females is a valuable commodity, which attracts younger prospective coalition partners in good condition regardless of body condition differences. Our results illustrate the general principle that grouping decisions cannot be understood by viewing partner choice criteria in isolation.
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synchronized vigilance while feeding in common eider Brood Rearing coalitions
Behavioral Ecology, 2011Co-Authors: Markus Ost, Tekla TieralaAbstract:The timing of vigilance and feeding in groups determines the efficiency of shared predator detection and foraging success. Behavioral monitoring of conspecifics remains controversial although synchronization is commonly observed and need not compromise predator detection. The within-group timing of vigilance shows inconsistent associations with group size, and whether nearby nongroup conspecifics affect this timing is poorly understood. Finally, it is unknown whether socially breeding parents time their activities to each other based on offspring predation risk. We studied diving common eider females (Somateria mollissima) in Brood-Rearing coalitions subject to gull predation of ducklings. The within-group timing of vigilance was determined by comparing observed collective vigilance, the proportion of time during which at least 1 adult group member is vigilant, with that expected assuming independent timing of activities. We determined the predictors of within-group timing of vigilance, observed collective vigilance, individual vigilance, frequency of nearby nongroup females (group outsiders), and incidence of alarm reactions. Vigilance was synchronized regardless of Brood composition. Synchronization and observed collective vigilance increased with female group size, whereas synchronization decreased with increasing ratios of ducklings to tending females. Individual vigilance increased in the presence of gull alarms. Within-group timing of activities was unrelated to the presence of group outsiders, but Broods with fewer ducklings (less predation dilution) were more often associated with group outsiders, the frequency of which was negatively associated with the incidence of gull alarms. Increased offspring predation risk thus reduces overlapping vigilance among adult group members and enhances attraction to nearby nongroup conspecifics. Key words: antipredator behavior, common eider, group living, parental care, risk dilution, synchronization of vigilance. [Behav Ecol]
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social and maternal factors affecting duckling survival in eiders somateria mollissima
Journal of Animal Ecology, 2008Co-Authors: Markus Ost, Barry D Smith, Mikael KilpiAbstract:1. With the aid of a novel survivorship model, an 8-year field study of social and maternal factors affecting duckling survival in eiders (Somateria mollissima) revealed that duckling survival probability varies in accordance with maternal Brood-Rearing strategy. This variability in survival provides compelling evidence of different annual fitness consequences between females that share Brood-Rearing and those that tend their Broods alone. Consequently, as prebreeding survival is often a major source of individual variation in lifetime reproductive success, a female's annual, state-dependent (e.g. condition) choice of a Brood-Rearing strategy can be a critical fitness decision. 2. Variance in duckling survival among lone tender Broods was best explained by a model with significant interannual variability in survival, and survivorship tending to increase with increasing clutch size at hatch. Clutch size was correlated positively with female condition. Hatch date and female body condition together affected duckling survival, but their contributions are confounded. We were unable to identify a relationship between female age or experience and duckling survival. 3. Variance in duckling survival among multifemale Brood-Rearing coalitions was best explained by a model that included the number of tenders, the number of ducklings and interannual variation in how their ratio affected survivorship. Hatch date did not significantly influence survival. 4. Expected duckling survival is higher in early life for lone tenders when compared with multifemale Brood-Rearing coalitions. However, as ducklings approach 2-3 weeks of age, two or three females was the optimal number of tenders to maximize daily duckling survival. The survivorship advantage of multifemale Brood-Rearing coalitions was most evident in years of average survival. 5. The observed frequency distribution of female group sizes corresponds with the distribution of offspring survival probabilities for these groups. Evidence for optimal group sizes in nature is rare, but the most likely candidates may be groups of unrelated animals where entry is controlled by the group members, such as for female eiders. 6. Our study demonstrates that differences in social factors can lead to different predictions of lifetime reproductive success in species with shared parental care of self-feeding young.
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aggressive females seize central positions and show increased vigilance in Brood Rearing coalitions of eiders
Animal Behaviour, 2007Co-Authors: Markus Ost, Kim Jaatinen, Benjamin B SteeleAbstract:Decreased risk of predation is a key benefit of group living, and selfish herd theory predicts competition for the relative safety of central positions. Spatial position also affects behaviour, as individuals trade-off their feeding and vigilance to mitigate the risk of predation. Female eiders, Somateria mollissima, often pool their Broods and share Brood Rearing, and anti-predatory vigilance is a core parental care activity. Females are assumed to trade-off vigilance and feeding, as efficient recovery of condition is crucial for energetically stressed postincubating females. Evidence shows that a female's own ducklings are closer to her than unrelated young in amalgamated Broods and that predation of ducklings by gulls is edge biased, so a female's spatial position should correlate with the survival prospects of her Brood. We identified determinants of female spatial position (aggression, structural size, body weight, age, clutch size) within multifemale Brood-Rearing coalitions, and explored whether spatial position affected female activities. Female aggression frequency was the only significant predictor of centrality in Brood-Rearing coalitions, and female age was positively associated with aggression. Investment in vigilance, but not investment in feeding, increased with spatial centrality; instead, central females devoted less time to other activities (resting, preening and moving). We conclude that central eider females do not need to trade-off vigilance and feeding. Heavy body weight did not guarantee a favourable position in Brood-Rearing coalitions, which may help explain our previous finding that female eiders in best body condition when their Brood hatches tend their Brood alone.
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parental effort and reproductive skew in coalitions of Brood Rearing female common eiders
The American Naturalist, 2007Co-Authors: Markus Ost, Mikael Kilpi, Colin W Clark, Ronald C YdenbergAbstract:Members of breeding groups face conflicts over parental effort when balancing antipredatory vigilance and feeding. Empirical evidence has shown disparate responses to manipulations of parental effort. We develop a model in which we determine the evolutionarily stable effort of partners given their body conditions, allowing the benefits of shared care to be unevenly divided, and we test this model's predictions with data on common eiders (Somateria mollis- sima). Eiders show uniparental female care; females may share Brood Rearing, or they may tend alone, and their body condition at hatching of the young shows large environmentally induced variation. The model predicts that parental effort (vigilance) in a coalition is lower than when tending alone, controlling for parental condition; this prediction is supported by the data. The parental effort in a coalition should be positively correlated with body condition, and this pre- diction is also supported. Finally, parental effort should increase when partner condition decreases and vice versa; this prediction is partially supported. The Nash bargaining game may provide promising av- enues by which to determine the precise settlement of reproductive skew and effort between coalition partners in the future.
Mikael Kilpi - One of the best experts on this subject based on the ideXlab platform.
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social and maternal factors affecting duckling survival in eiders somateria mollissima
Journal of Animal Ecology, 2008Co-Authors: Markus Ost, Barry D Smith, Mikael KilpiAbstract:1. With the aid of a novel survivorship model, an 8-year field study of social and maternal factors affecting duckling survival in eiders (Somateria mollissima) revealed that duckling survival probability varies in accordance with maternal Brood-Rearing strategy. This variability in survival provides compelling evidence of different annual fitness consequences between females that share Brood-Rearing and those that tend their Broods alone. Consequently, as prebreeding survival is often a major source of individual variation in lifetime reproductive success, a female's annual, state-dependent (e.g. condition) choice of a Brood-Rearing strategy can be a critical fitness decision. 2. Variance in duckling survival among lone tender Broods was best explained by a model with significant interannual variability in survival, and survivorship tending to increase with increasing clutch size at hatch. Clutch size was correlated positively with female condition. Hatch date and female body condition together affected duckling survival, but their contributions are confounded. We were unable to identify a relationship between female age or experience and duckling survival. 3. Variance in duckling survival among multifemale Brood-Rearing coalitions was best explained by a model that included the number of tenders, the number of ducklings and interannual variation in how their ratio affected survivorship. Hatch date did not significantly influence survival. 4. Expected duckling survival is higher in early life for lone tenders when compared with multifemale Brood-Rearing coalitions. However, as ducklings approach 2-3 weeks of age, two or three females was the optimal number of tenders to maximize daily duckling survival. The survivorship advantage of multifemale Brood-Rearing coalitions was most evident in years of average survival. 5. The observed frequency distribution of female group sizes corresponds with the distribution of offspring survival probabilities for these groups. Evidence for optimal group sizes in nature is rare, but the most likely candidates may be groups of unrelated animals where entry is controlled by the group members, such as for female eiders. 6. Our study demonstrates that differences in social factors can lead to different predictions of lifetime reproductive success in species with shared parental care of self-feeding young.
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parental effort and reproductive skew in coalitions of Brood Rearing female common eiders
The American Naturalist, 2007Co-Authors: Markus Ost, Mikael Kilpi, Colin W Clark, Ronald C YdenbergAbstract:Members of breeding groups face conflicts over parental effort when balancing antipredatory vigilance and feeding. Empirical evidence has shown disparate responses to manipulations of parental effort. We develop a model in which we determine the evolutionarily stable effort of partners given their body conditions, allowing the benefits of shared care to be unevenly divided, and we test this model's predictions with data on common eiders (Somateria mollis- sima). Eiders show uniparental female care; females may share Brood Rearing, or they may tend alone, and their body condition at hatching of the young shows large environmentally induced variation. The model predicts that parental effort (vigilance) in a coalition is lower than when tending alone, controlling for parental condition; this prediction is supported by the data. The parental effort in a coalition should be positively correlated with body condition, and this pre- diction is also supported. Finally, parental effort should increase when partner condition decreases and vice versa; this prediction is partially supported. The Nash bargaining game may provide promising av- enues by which to determine the precise settlement of reproductive skew and effort between coalition partners in the future.
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eider females form non kin Brood Rearing coalitions
Molecular Ecology, 2005Co-Authors: Markus Ost, Emma I K Vitikainen, Peter Waldeck, Liselotte Sundstrom, Kai Lindstrom, Tuula E Hollmen, Christian J Franson, Mikael KilpiAbstract:Kin selection is a powerful tool for understanding cooperation among individuals, yet its role as the sole explanation of cooperative societies has recently been challenged on empirical grounds. These studies suggest that direct benefits of cooperation are often overlooked, and that partner choice may be a widespread mechanism of cooperation. Female eider ducks (Somateria mollissima) may rear Broods alone, or they may pool their Broods and share Brood-Rearing. Females are philopatric, and it has been suggested that colonies may largely consist of related females, which could promote interactions among relatives. Alternatively, shared Brood care could be random with respect to relatedness, either because Brood amalgamations are accidental and nonadaptive, or through group augmentation, assuming that the fitness of all group members increases with group size. We tested these alternatives by measuring the relatedness of co-tending eider females in enduring coalitions with microsatellite markers. Females formed enduring Brood-Rearing coalitions with each other at random with respect to relatedness. However, based on previous data, partner choice is nonrandom and dependent on female body condition. We discuss potential mechanisms underlying eider communal Brood-Rearing decisions, which may be driven by the specific ecological conditions under which sociality has evolved in this species.
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condition and coalition formation by Brood Rearing common eider females
Behavioral Ecology, 2003Co-Authors: Markus Ost, Mikael Kilpi, Ronald C Ydenberg, Kai LindstromAbstract:Partner choice is important in nature, and partnerships or coalitions within which reproduction is shared are the subject of growing interest. However, little attention has been given to questions of which individuals are suitable partners and why. Common eider (Somateria mollissima) females sometimes pool their Broods and share Brood-Rearing duties, and body condition affects care decisions. We constructed a model in which females, based on their body condition and the structure of the joint Brood, assess the fitness consequences of joining a coalition versus tending for young alone. We tested the model's predictions by comparing data on the condition of females in enduring and transient coalitions. Our model showed that the range of acceptable Brood arrays in a female coalition decreases with increasing condition of the female, so females tending alone should be in better condition than multifemale tenders. This prediction is in agreement with previous data. The model also predicts that females in good condition should join coalitions with females in poor condition and not with other females in good condition. This prediction was also supported by data: in enduring two-female coalitions, the positive correlation between the better female's condition and the difference in condition between the two females was stronger than would be expected by random grouping of females. In contrast, in transient coalitions of females, this correlation did not differ from the correlation expected under random grouping. Model assumptions seem to fit with eider natural history, and the model may prove to be a useful way to study Brood amalgamation behavior of waterfowl in general.
John R. Harbo - One of the best experts on this subject based on the ideXlab platform.
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Effect of Brood Rearing on honey consumption and the survival of worker honey bees
Journal of Apicultural Research, 1993Co-Authors: John R. HarboAbstract:SUMMARYThe cost of Rearing a worker honey bee (Apis mellifera) was measured in terms of honey lost by the colony and the lifespan of the adult worker bees. Test colonies for each experiment were created by collecting bees from many different sources into a large cage and then subdividing those bees to make a group of uniform colonies. Colonies were evaluated outdoors in Baton Rouge, Louisiana, USA, during February when there was pollen but no nectar for bees to collect. Brood production did not have a significant effect on adult survival during the first cycle of Brood Rearing, but colonies that reared more Brood during the first Brood cycle had greater adult mortality during the next Brood cycle. Bees used 121 g of honey to produce 1 000 cells of mixed-aged Brood (eggs, larvae and pupae in a normal Brood nest) and about 163 mg of honey to rear one worker bee to the pupal stage. In colonies containing Brood of all stages, the weight of Brood was nearly equal to (about 25% less than) the weight of honey th...
Paul L Flint - One of the best experts on this subject based on the ideXlab platform.
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survival of common eider somateria mollissima adult females and ducklings during Brood Rearing
Wildfowl, 1998Co-Authors: Paul L Flint, Christine L Moran, Jason L SchamberAbstract:We studied survival of adult female and duckling Common Eiders during Brood Rearing at two sties o the Yukon-Kuskokwim Delta, Alaska, in 1997. Duckling survival to 30 days of age was 19% 10% (95% CI). Seventy-three percent of radio-marked adult females had lost all their ducklings by 30 days after hatch. Duckling survival was not related to hatch date. We estimate an average of 0.84 ducklings fledged per adult female radio-marked at hatch. Most Broods moved to salt water within 15 days of hatch. Adult female survival during the first 30 days of Brood Rearing was 96 6% (95% CI). Mortality of adult females during Brood Rearing is probably higher than during other times of the year.
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habitat use by nesting and Brood Rearing northern pintails on the yukon kuskokwim delta alaska
Journal of Wildlife Management, 1997Co-Authors: James B Grand, Paul L Flint, Patricia J HeglundAbstract:We studied habitat use by nesting and Brood-Rearing northern pintails (Anas acuta) on the coastal Yukon-Kuskokwim (Y-K) Delta, 1991-93. We used a digital habitat map constructed from color infrared aerial photos to assign habitat types to nest and Brood locations and estimate habitat availability. Sixty-nine percent of females nested on slough banks in highly saline, tidally influenced habitats where we observed few mammalian predators. Nesting pintails likely preferred slough banks because they were higher and well drained early in the nesting season. Radiomarked females selected moderately saline habitats that were only occasionally or rarely influenced by tides for Brood Rearing. Eighty percent of females that nested in saline habitats moved their Broods to less saline habitats, and those that nested in preferred Brood-Rearing habitats never moved to more saline habitats to rear their Broods. Managers should be aware that in coastal wetlands the proximity of good-quality nesting and Brood Rearing habitats is important, and the distribution of nesting pintails may not reflect the distribution of Broods and vice versa.
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survival of juvenile black brant during Brood Rearing
Journal of Wildlife Management, 1995Co-Authors: Paul L Flint, James S Sedinger, Kenneth H PollockAbstract:Survival of young is an important and poorly understood component of waterfowl productivity. We estimated survival of black brant (Branta bernicla nigricans) goslings during summers 1987-89 on the Yukon-Kuskokwim Delta, Alaska, to determine timing and magnitude of gosling mortality and to compare methods of estimating gosling survival. Eighty-two percent of radio-tagged adult females (n = 61) fledged ≥1 gosling (Brood success). We estimated survival of goslings within Broods by 3 methods: (1) changes in mean Brood size through time, (2) observation of goslings associated with marked adults, and (3) age ratios of brant captured in banding drives. Estimates of gosling survival within successful Broods averaged 81% and ranged from 66 to 92%. Combining Brood success and gosling survival within successful Broods yielded estimates of overall gosling survival that averaged 68%, ranging from 79% in 1987 to 56% in 1989. Eighty-two percent of gosling mortality occurred in the first 15 days. Estimates of survival on the basis of age ratios of birds captured in banding drives are biased low. Our estimates of average gosling survival are higher than reported for other species of geese.
Kai Lindstrom - One of the best experts on this subject based on the ideXlab platform.
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eider females form non kin Brood Rearing coalitions
Molecular Ecology, 2005Co-Authors: Markus Ost, Emma I K Vitikainen, Peter Waldeck, Liselotte Sundstrom, Kai Lindstrom, Tuula E Hollmen, Christian J Franson, Mikael KilpiAbstract:Kin selection is a powerful tool for understanding cooperation among individuals, yet its role as the sole explanation of cooperative societies has recently been challenged on empirical grounds. These studies suggest that direct benefits of cooperation are often overlooked, and that partner choice may be a widespread mechanism of cooperation. Female eider ducks (Somateria mollissima) may rear Broods alone, or they may pool their Broods and share Brood-Rearing. Females are philopatric, and it has been suggested that colonies may largely consist of related females, which could promote interactions among relatives. Alternatively, shared Brood care could be random with respect to relatedness, either because Brood amalgamations are accidental and nonadaptive, or through group augmentation, assuming that the fitness of all group members increases with group size. We tested these alternatives by measuring the relatedness of co-tending eider females in enduring coalitions with microsatellite markers. Females formed enduring Brood-Rearing coalitions with each other at random with respect to relatedness. However, based on previous data, partner choice is nonrandom and dependent on female body condition. We discuss potential mechanisms underlying eider communal Brood-Rearing decisions, which may be driven by the specific ecological conditions under which sociality has evolved in this species.
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condition and coalition formation by Brood Rearing common eider females
Behavioral Ecology, 2003Co-Authors: Markus Ost, Mikael Kilpi, Ronald C Ydenberg, Kai LindstromAbstract:Partner choice is important in nature, and partnerships or coalitions within which reproduction is shared are the subject of growing interest. However, little attention has been given to questions of which individuals are suitable partners and why. Common eider (Somateria mollissima) females sometimes pool their Broods and share Brood-Rearing duties, and body condition affects care decisions. We constructed a model in which females, based on their body condition and the structure of the joint Brood, assess the fitness consequences of joining a coalition versus tending for young alone. We tested the model's predictions by comparing data on the condition of females in enduring and transient coalitions. Our model showed that the range of acceptable Brood arrays in a female coalition decreases with increasing condition of the female, so females tending alone should be in better condition than multifemale tenders. This prediction is in agreement with previous data. The model also predicts that females in good condition should join coalitions with females in poor condition and not with other females in good condition. This prediction was also supported by data: in enduring two-female coalitions, the positive correlation between the better female's condition and the difference in condition between the two females was stronger than would be expected by random grouping of females. In contrast, in transient coalitions of females, this correlation did not differ from the correlation expected under random grouping. Model assumptions seem to fit with eider natural history, and the model may prove to be a useful way to study Brood amalgamation behavior of waterfowl in general.
